Is a diamond-encrusted Mercedes a sign of progress, conspicuous consumption, or extraordinary gaudiness? This Mercedes-Benz SL550 apparently appeared at a Dubai Auto Show recently. It’s unclear whether the diamonds are real or fake, but in either case, the effect isn’t subtle.

It’s the sort of car you wouldn’t find in J.K. Rowling’s garage. Rowling, the author of the Harry Potter series, lives what she calls a very “mundane” lifestyle despite having earned over a billion dollars in royalties and merchandise from the Harry Potter books and films. In from last year, she explains ‘I’ve got a mental amount I can’t spend beyond. I limit myself to what I think I would be justified in spending on frivolity.’ Sensible indeed (though it should be noted she has a healthy travel budget).

The reason she hasn’t entirely blinged out seems to be that she came into her wealth later in life. She also knows what it’s like to have nothing, living on 70 pounds a week state benefits for a period earlier in her career. Now she can likely afford the diamond-encrusted Mercedes, but she doesn’t want it.

Luxury is knowing what you want and why you want it.